Program Tinh_tong;

Var n, x, i, S : Integer;

Begin

Write ('Hay nhap n la : '); Readln (n);

i := 0; S := 0;

While i < n do

      Begin

            i := i + 1;

            Write ('Nhap so thu ',i,' = '); Readln (x);

            if x mod 3 = 0 then S := S + x;

      End;

Writeln ('Tong cac so chia het cho 3 la : ',S);

Readln

End.

program C;
uses crt;
var a:array[1..100] of integer;
      n,i,s:integer;
begin
      clrscr;
      write('Nhap so luong phan tu: '); readln(n);
      s:=0;
      for i:=1 to n do
            begin
                  write('a[',i,']: '); readln(a[i]);
                  if a[i] mod 3=0 then s:=s+a[i];
            end;
      write('Tong cac so chia het cho 3: ',s);
      readln;
end.